In general, tires are configured in such a manner as to include a plurality of tire rubber members and a plurality of reinforcement members which are mainly made up of cords. In a representative tire, as is shown in FIG. 1, respective portions such as an inner liner rubber portion 1, a tread rubber portion 2, side wall rubber portions 3, rim strip rubber portions 4 and the like are formed by rubber members which match properties required for the respective portions and these rubber members are combined with a carcass layer 5 which constitutes a cord-contained reinforcement member, a belt layer 6 and bead portions 7 to thereby make up a tire T1.
To build rubber members which make up the respective portions, rubber materials were extruded continuously to be built into rubber strips from an extruding machine via dies which match cross sectional shapes of the respective rubber members, and thereafter, the extruded rubber strips were cut to constant dimensions to thereby obtain target rubber members. In building a tire, the rubber members were sequentially affixed together on a rotational support element such as a building drum.
In addition, in recent years, in order to reduce the rolling resistance of a tire, tread rubbers have been developed which use silica instead of carbon black as a strengthening agent. However, since the tread rubbers have an electric resistance which is higher than that of tread rubbers which is compounded with only carbon black, there has been caused a problem that static electricity conducted from a vehicle body or electricity generated by virtue of internal friction when rubber deforms is accumulated. Then, there have been proposed pneumatic tires with a static elimination function which are made up in parallel of a non-conductive rubber which contains silica or the like and a conductive rubber which is compounded with carbon black or the like so that electricity generated in the vehicle body is made to be discharged to the road surface from a tread surface thereof.
For example, there has been proposed a method for building up a tread portion with a static elimination function by winding sequentially both a non-conductive rubber strip member and a highly conductive rubber strip member along a circumferential direction of a tire in a spiral fashion in such a manner that the non-conductive and highly conductive rubber strip members are disposed in an alternate fashion (for example, refer to Patent Document No. 1 below).
However, to satisfy the demand for a further reduced rolling resistance, there has been proposed a constitution in which a non-conductive rubber strip member and a conductive rubber strip member are disposed alternately in part of a tread portion in a tire width direction such as both side portions of the tread portion in the tire width direction or a central portion of the tread portion in the tire width direction. However, the following problem will emerge in building the tread portion using the method described above.
Namely, in the aforesaid building method, since the respective rubber strip members are disposed alternately by winding the non-conductive rubber strip member and the conductive rubber strip member on to the drum in an overlapping fashion, the rotation of the drum has to be stopped in the midst of the winding operation in order to start the supply of a highly conductive rubber strip member, this resulting in a problem that a fabrication cycle time is lengthened largely.    Patent Document No. 1: JP-A-2004-338621